Abstract
We have deduced the emission probability of the 447-keV γ ray from the ϵ+β+ decay of Ceg137 (9.0 h) relative to that of the 254-keV γ ray from the Cem137 (34.4 h) decay in transient equilibrium. The time-dependent factor in transient equilibrium was applied following the Bateman equation for a radioactive decay chain. The isotope was produced via the La139(p,3n)Cem,g137 reaction by bombarding natLa with a proton beam from the 88-in. cyclotron at Lawrence Berkeley National Laboratory. γ-ray intensities were measured using an HPGe detector. The emission probability for the 447-keV γ ray deduced in this work is 1.21(3) (that is 1.21 ± 0.03) per hundred parent decays, which differs significantly from an earlier published value of 2.24(10). We identify the source of this discrepancy to be an incorrect use of the time-dependent factor. Additionally, we have deduced the emission probability of the 504-keV γ ray from the decay of Yg85 (2.68 h) relative to that of the 232-keV γ ray from the Srm85 (1.127 h) decay in transient equilibrium. The isotope was produced via the Sr86(p,2n)Yg85 reaction by bombarding SrCO386 with a proton beam at the same facility. The study confirms the assumption of the time-dependent correction for recommending the emission probability of the 504-keV γ ray in the literature. Our work highlights the importance of explicit description by authors of any time-dependent correction they have made when reporting γ-ray intensities for nuclides in transient equilibrium. The need and significance of accurate and precise decay data of Ceg137 and Yg85 in basic science and medicine is briefly outlined.
| Original language | English |
|---|---|
| Article number | 064619 |
| Journal | Physical Review C |
| Volume | 101 |
| Issue number | 6 |
| DOIs | |
| State | Published - Jun 2020 |
Funding
The authors wish to thank the reviewer for several useful comments and suggestions regarding the manuscript. We wish to express our gratitude to B. Ninemire, N. Brickner, T. Gimpel, and S. Small for their support during experimental setup and for the 88-in. cyclotron operations. We thank S. Spellerberg and K. Giesen (FZJ) for preparing the samples. This work was performed under the auspices of the US Department of Energy by Lawrence Berkeley National Laboratory under Contracts No. LAB16-1588 NSD and No. DE-AC02-05CH11231.